Electrical plug connector



July 15, 1941; i K, PERKINS I 2,249,619

ELECTI'IICAL PLUG CONNECTOR Original Filed Sept. 30, 1939 Sheets-Sheet l Has. 23

KENNETH PERKINS y I K. PEEQKINS 2,249,619

- ELECTRICAL PLUG CONNECTOR 0rig ina1 Filed Sept. 30-, 1939 I 2. Sheets-Sheet 2 KENNETH PERKINS the two halves of the plug-member.

Patented July 15, 1941 ELECTRICAL PLUG CONNECTOR Kenneth Perkins, Scotch Plains, N. J., assignor to The Singer Manufacturing Company, Elizabeth, N. J., a corporation of New Jersey Original application September so, 1939, Serial No. 297,268. Divided and this application April 12, 1940, Serial No. 329,262

4 Claims.

This invention relates to electrical plug-connectors adapted, more particularly, for use with motor-driven family sewing machines.

An object of the invention is to provide a plugconnector having improved casing and contact elements which are readily manufactured and assembled.

Another object of the invention is to provide a plug-connector the live metallic parts of which are at no time so exposed that they can be touched by anyone.

A further object of the invention is the incorporation in the connector of an exposed ground contact which is well separated and thoroughly insulated from the unexposed live contacts.

Still further, the invention has for an object to provide a plug-connector the casing of which is provided with special cord inlets adapting it particularly to the requirements of electric sewing machine outfits.

With the above and other objects in view, as will hereinafter appear, the invention comprises the devices, combinations and arrangements of parts hereinafter set forth and illustrated in the accompanying drawings of a preferred embodiment of the invention, from which the several features of the invention and the advantages attained thereby will be readily understood by those skilled in the art.

In the accompanying drawings, Fig. 1 is a perspective View of the motor bracket of an electric sewing machine carrying a connector the plugmember of which embodies the invention. Fig. 2 is a perspective view of the connector socketmember shown in Fig. 1 which is adapted to receive a plug-member embodying the invention. Fig. 3 is a perspective view of the plug-member, complete. Figs. 4 and 5 are perspective views of Fig. 6 is a central transverse section through the plugmember. Fig. '7 is a perspective View of a special rubber plug for use with the plug-connector when wired for use with a treadle or knee operated rheostat. Fig. 8 is a diagram of connections for the plug-connector when used with a knee or. treadle operated controller built into a sewing machine cabinet, and Fig. 9 is a diagram of connections for the connector when used with a footoperated controller to be placed on the floor 5 where desired.

This application is a division of my copending application Serial No. 297,268, filed Sept. 30, 1939. I represents the 'cast iron motor-supporting bracket of a sewing machine, such as represented in U. S. Patent No. 1,488,234, dated Mar.v 25, 1924. As shown in said patent this bracket has a slotted foot portion 2, which is bolted to the bracket-arm standard of a sewing machine, and an inclined end-portion 3 which carries the sewing machine driving motor. is also formed with a seat 4 to which is secured by the screw 5 a socket-member 6, suitable to re-.

ceive the present plug-connector. The socketmember 6 may comprise a casing of molded in,- sulation material, preferably Bakelite, having a plug-receiving cavity 1 from the bottom end wall 8 of which project the fiat connector-blades 9 standing in edge-to-edge spaced relation. There may be fastened under the head of the screw 5 a ground contact blade I0 which is in metallic connection with the iron bracket I and I external groove I5 in which may be disposed the reversely bent end of the spring ground-contact I6 the shank I! of which is held by the headedover end of the metal insert I8, in which the binding screw I9 for a ground-conductor 20 is threaded.

The plug-casing I I is made of two molded separable sections 2| and 22 of Bakelite held together by screws 23 and snap-rings 24 which latter embrace the oppositely extending conductor-receiving coaxial tubular extensions25, 26 formed at the base of the penetrant portion I2 of the plug casing. These extensions 25, 26 are formed internally with the strain-relieving ribs 21 which grip the conductor-cord insulation when the parts are assembled. The longitudinal axes of the coaxial tubular projections 25, 26 lie substantially in the parting plane of the separable sections 2|, 22.

The plug-section 22 is preferably formed internally with three square posts 28 which are spaced apart and from the side walls of the section 22. Into the grooved top ends of these posts are riveted, by metal inserts, the shanks of the return-bent spring-contacts 29 which all face in the same direction and are within the openings I3 so as to be engaged by the contact blades The bracket I 9 when the plug H is inserted in the socketcavity 1. Binding screws 30 for the lead-in wires are threaded into the metal inserts by which the contacts 29 are riveted in position. One of the side Walls 3|, Fig. 6, is formed with contactspring rest grooves 32.

The plug-section 2| is formed with the internal tubular portions 33 which surround the fastening screws 23. It is also formed with a cavity 34 for the lead-in wires.

The plug-member l I has at the base of the reduced penetrant portion l2, a vertical planar stop-wall I2 which contacts the edge of the receiving end of the socket-member 6 and definitely limits the insertion distance of the plugmember II therein. It will also be noted that the outer surfaces at one side of the plug-member are stepped; the vertical stop-wall l2 constituting a step riser and the adjoining portions of the penetrant and thicker ends of the casing constituting the step treads. The ground contact 16 is similarly stepped and is thus made long enough to possess the requisite resiliency.

It will be further noted that the shanks of the contacts 29, Fig. 6, bridge a gap between the rest grooves 32 and posts 28. These gaps permit the blade shanks to flex downwardly when the prongs 9, Fig. 2, engage and depress the return bent portions of the contacts 29. This provision relieves the strain to which the bends at the ends of the contacts 29 are subjected.

When the motor-speed controller 35 is built into a sewing machine cabinet it is more conveniently wired to the socket-member 6, together With the light L and motor M, as shown in Fig.

8. In this case three lead-in wires, including two current-supply wires and one ground wire 20 are led through the opening of the tubular projection 2B of the plug-member II and connected, as shown, to the two outside contacts 29 and to the ground-contact IS. The center contact 29 is not used. The tubular lead-in projection 25 is not used and is filled by the double-headed rubber plug 36.

When the motor-speed controller 35 is to be placed on the floor or moved about-as desired, it is more convenient to wire it to the plug-member I I, as shown in Fig. 9. Here, the connections of the current-supply wires and ground wire 20 are the same as in Fig. 8, but the controller leads 37, which run through the tubular extension 25, vacated by the rubber plug 36, are connected to the center and right hand contacts 29.

When the halves of the plug-member II are fastened together, the live contacts 29 therewithin are completely covered and cannot be touched by anyone.

The current supply cord runs, without kinking, from a wall plug at the rear of the machine into the rearwardly directed cord inlet extension 26 while the cord of the controller, which is normally located on the floor in front of the machine runs, without kinking, into the forwardly directed cord inlet extension 25.

The device is structurally well adapted for convenient use with the various known types of electrically lighted and motor-driven sewing machine outfits.

Having thus set forth the nature of the invention what I claim herein is:

1. A connector member comprising a casing of insulation material formed in two half-sections and having a cavity therewithin, and a parting plane, one of said half-sections being formed with internal posts projecting into said cavity in a direction transverse to said parting plane, said posts being formed at their free ends with shallow flat-bottomed grooves defining seats parallel to said parting plane, a set of contact blade springs having thin shank ends secured flatwise to said seats and having return bends at their 7 other ends, said post-containing casing section having steady-rest grooves in a wall portion thereof spaced from said posts, said steady-rest grooves receiving the bends of said contact springs, the other casing section having contactprong-admission grooves in register with said steady-rest grooves.

2. A connector member comprising a casing of insulation material formed in two half-sections and having a cavity therewithin and a parting plane, one of said sections being formed at one side with a stepped outer wall having two tread portions and an intermediate riser portion, all of which portions are formed with a stepped ground-contact-blade receiving groove having two treads and an intermediate riser portion,

and a stepped ground-contact spring-blade having two treads and an intermediate riser portion disposed in said groove and secured at one end to one of said treads.

3. A connector comprising a hollow casing having a penetrant end-portion and a thicker opposite end-portion, a stepped ground-contact spring blade having two treads and an intermediate riser portion secured by one of said treads to the thicker end portion of said casing, externally of the latter, the other tread extending onto and toward the free end of said penetrant portion externally of the latter, and live contact elements mounted within the penetrant portion of said hollow casing.

4. A connector member comprising a casing of insulation material formed in two separable sections and having a cavity therewithin, one of said sections being formed with an internal post projecting into and spaced from the walls of said cavity, said post being formed at its free end with a seat transverse to the direction of length of said post, a contact blade spring having a thin shank end secured to said seat and having a return bend at its other end, said post-containing casing section having a steady-rest groove in a wall portion thereof spaced from said post, said steady-rest groove receiving the bend of said contact spring, said casing having a contactprong-admission groove in register with said steady-rest groove.

KENNETH PERKINS. 

